Crysis 2 uses a development of the Crysis Warhead engine optimised for efficiency but adds DirectX 11 support via a patch and this can be quite demanding. As, for example, with tessellation, implemented abusively in collaboration with NVIDIA with the aim of causing Radeon performance to plummet. We have already exposed this issue here
We measured performance with Fraps on version 1.9 of the game.
The GeForce GTX 680 enjoys a small improvement with the latest drivers, which allows it to position itself between the Radeon HD 7970s.